ptarray_grid_in_place()

void ptarray_grid_in_place	(	POINTARRAY *	pa,
		gridspec *	grid
	)

Snap to grid.

Definition at line 2222 of file ptarray.c.

{
        uint32_t j = 0;
        POINT4D *p, *p_out = NULL;
        double x, y, z = 0, m = 0;
        uint32_t ndims = FLAGS_NDIMS(pa->flags);
        uint32_t has_z = FLAGS_GET_Z(pa->flags);
        uint32_t has_m = FLAGS_GET_M(pa->flags);
 
        for (uint32_t i = 0; i < pa->npoints; i++)
        {
                /* Look straight into the abyss */
                p = (POINT4D *)(getPoint_internal(pa, i));
                x = p->x;
                y = p->y;
                if (ndims > 2)
                        z = p->z;
                if (ndims > 3)
                        m = p->m;
 
                /*
                 * See https://github.com/libgeos/geos/pull/956
                 * We use scale for rounding when gridsize is < 1 and
                 * gridsize for rounding when scale < 1.
                 */
                if (grid->xsize > 0) {
                        if (grid->xsize < 1)
                                x = rint((x - grid->ipx) * grid->xscale) / grid->xscale + grid->ipx;
                        else
                                x = rint((x - grid->ipx) / grid->xsize) * grid->xsize + grid->ipx;
                }
 
                if (grid->ysize > 0) {
                        if (grid->ysize < 1)
                                y = rint((y - grid->ipy) * grid->yscale) / grid->yscale + grid->ipy;
                        else
                                y = rint((y - grid->ipy) / grid->ysize) * grid->ysize + grid->ipy;
                }
 
                /* Read and round this point */
                /* Z is always in third position */
                if (has_z && grid->zsize > 0)
                        z = rint((z - grid->ipz) / grid->zsize) * grid->zsize + grid->ipz;
 
                /* M might be in 3rd or 4th position */
                if (has_m && grid->msize > 0)
                {
                        /* In POINT ZM, M is in 4th position, in POINT M, M is in 3rd position which is Z in POINT4D */
                        if (has_z)
                                m = rint((m - grid->ipm) / grid->msize) * grid->msize + grid->ipm;
                        else
                                z = rint((z - grid->ipm) / grid->msize) * grid->msize + grid->ipm;
                }
 
                /* Skip duplicates */
                if (p_out &&
                    p_out->x == x &&
                    p_out->y == y &&
                    (ndims > 2 ? p_out->z == z : 1) &&
                    (ndims > 3 ? p_out->m == m : 1))
                {
                        continue;
                }
 
                /* Write rounded values into the next available point */
                p_out = (POINT4D *)(getPoint_internal(pa, j++));
                p_out->x = x;
                p_out->y = y;
                if (ndims > 2)
                        p_out->z = z;
                if (ndims > 3)
                        p_out->m = m;
        }
 
        /* Update output ptarray length */
        pa->npoints = j;
        return;
}

References POINTARRAY::flags, FLAGS_GET_M, FLAGS_GET_Z, FLAGS_NDIMS, getPoint_internal(), gridspec_t::ipm, gridspec_t::ipx, gridspec_t::ipy, gridspec_t::ipz, POINT4D::m, gridspec_t::msize, POINTARRAY::npoints, POINT4D::x, gridspec_t::xscale, gridspec_t::xsize, POINT4D::y, gridspec_t::yscale, gridspec_t::ysize, POINT4D::z, and gridspec_t::zsize.

Referenced by lwgeom_grid_in_place().

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